German Patent No. 31 22 861 describes a device for measuring the absolute pressure of air. This device has an amperometric sensor that work on the limiting diffusion current principle, called a polarographic measuring cell there, which is made up of an oxygen ion-conducting solid electrolyte element and two electrodes situated on opposite sides of the solid electrolyte element, of which the electrode operated as a cathode is exposed to the air that is to be measured via a porous diffusion layer that covers the electrode. A constant direct voltage is applied to the electrodes. As a result of the electrochemical reduction of the oxygen, the latter is used up at the cathode. The concentration gradient of the oxygen thus created, brings about a diffusion current of oxygen through the diffusion layer. The concentration gradient is the controlling factor for the reduced oxygen quantity, and thus for the measuring signal. The pores in the diffusion layer preferably have a diameter that is small compared to the mean free path of the oxygen molecules. The transport of the oxygen ions, under these conditions, takes place above all by the so-called Knudsen diffusion, in which a strong pressure dependency of the diffusion current, and thus of the measuring signal, comes about. The device is also equipped with controlled heating, which heats the sensor or the measuring cell to a constant temperature above about 600° C.